Switch means for telethermometers



Dec. 20, 1932. c. H. KUHLMAN SWITCH MEANS FOR TELETHERMOMETERS Filed Dec. 25, 1929 QOOOj/y900 Patented Dec. 20, 1932 g UNITED STATES PATENT oFF cs CARL H. KUHLMAN, OF TOLEDO, OHIO, .ASSIGNOR TO THE AMERICAN TEMBERATURE INDICATING COMPANY, OF TOLEDO, OHIO, A CORPORATION OF OHIO SWITCH MEANS FOR TELETHERMOMETEBS This invention relates to electric current control.

This invention has utility when incorporated in selective station devices of telethermometers. I

Referring to the drawing Fig. 1 is a front view of a central station embodying the invention, with parts broken away, showing a remote device as effecting the station operation; 6

Fig. 2 is a wiring diagram;

Fig. 3 is a detail View in side elevation, parts being broken away, of an embodiment of the invention as to the switches in open position; 1 p

Fig. 4 is a fragmentary view of. the switches showing the mercury switch closed and the circuit still open;

Fig. 5 is a view similar to Fig. 3, but with the switches in fully closed position; and

Fig. 6 is a detail view of the container. Central station cabinet 1 is shown as having galvanometer instrument 2 with indicating needle 8. Remote station identification means 4 identify the adjacent push button switches 5. Push button 5 p as thrust into closed position is effective initially to connect terminal. 6 from remote station to terminal 7 *by a flexing operation. Further depression of the push button 5 connects additional switch terminal 8 in communication through line 9, adjustable rheostat 10, to electrical energy source 11. Line 12 from the opposite pole thereof extends to terminal 13 of WVheatstone bridge having therein the galvanometer 2.

This Wheatstone bridge has terminal 14 from which extends line 15 to terminal 7.

From terminal 16 of the WVheatstone bridge extends line 17 having branches through balancing resistances 18 and remote temperature affected resistances 19 from which extend lines 20 to the several switches 6. The temperature affected resistance at the remote 0 wardly from which protrude the push buttons 5, as held in outward position by spring arm 23 as an extension of the terminal 6. This sprlng arm 23 is shown as provided with clip 24 into which may be snapped container 25 herein shown as a closed end glass tube having at one end thereof a pair of terminals I p 26, 27. From the terminal 26 extends flexible connection 28 to the clip 24, thereby affording a direct connection through the extension 23 with the terminal 6.

From the terminal 27 extends flexible con nection 29 to the terminal 7. At the initial thrust inward of the push button 5, against the spring resistance of the terminal 6, the extension 23 with the clip 24 is so rocked from the'inclined position (Fig. 5) to position in Fig. 4, so that mercury in the container 25 rolls into switch closing position at the terminals 26, 27. As herein shown this is a supplemental switch closing beyond that of the closure between the terminals 6, 7, and approximates closing therewith.

In practice, in telethermomet-ers, the amperage and voltage are relatively low and the fluctuations for disclosing temperature of stations at cases 21, require a degree of accuracy responded to'in the device of this disclosure, for the terminals 26, 27, are at all times clean and the mercury 30 does not tend to disintegrate by any arcing in the sealed tube or container 25. Avoidance of any such arcing as effectin the mercury or terminals is attained herein because current flow does not occur through the switch 26, 30, 27, until after the mercury has come to-closed position and such current is cut off before the mercury has rolled away to switch opening position.

The depression of the push button 5 initially closing the mercury switch, upon further travel, effects the secondary flexing for bringing the terminals 7 the terminals 8. This additional switch 7, 8, completes the circuit for carrying electric current, and is in series with this mercury closed switch, as shown in Figs. 4, 5, the position in Fig. 5 being that for the closure of the 95 three switches, the switch 6,7, in parallel with the mercury switch, and the switch 7, 8, in series with the switch 6, 7, and the mercury switch. Upon release of the push button 5 after taking the reading disclosed by the 10 into closed position with needle 3, there is first the opening of the switch 7, 8, before the mercury has rolled free of the terminals 26, 27. This is a simple reliable switch of permanence, even at telethermometer locations in the fuel room where fumes pervade the region of the central sta tion and there is accordingly avoidance of deleterious action therefrom.

The duplication of the switches for the several selective branches, that is, the switch determined by terminals 6, 7, as a mechanical switch and the fluid switch as determined by the terminals 26, 27, closed by the mercury 30, has utility especially in the combination herein. The battery circuit as closed at the switches 7, 8, is of an amperage readily effective as a supply circuit. However, the current flowing for the branch in ascertaining the reading for temperature in the remote place in not only of relatively small current, but the variations therein involve features wherein accuracy in ascertaining such is important. \Vhile as heretofore suggested, open terminals 6, 7 may become contamin ated to increase the resistance there-at, it is practical to maintain a low resistance at the mercury switch. There is slight inertia delay in the mercury movement. However, these switches 6, 7 and 26, 27, approximate simultaneous closing especially in the normal depression of the push button 5.

However, should there be sudden depression of the push button 5, there may be slight delay in the mercury getting to closed position and such may even be a lag from the closing of the switch 7, 8. Were the switch 6, 7, eliminated under such circumstances, there would be a sudden throwing of the needle 3, tending to hammer such toward the extreme position. Omission of the mercury switch and the accumulation of deleterious matter to increase or disturb uniform resistance at the switch 6, 7, in the absence of the mercury switch would be an additional or another factor in causing the needle 3 to float about or make inaccurate disclosure of the circuit condition. It accordingly follows that with these switches in parallel, the switch 6, T, in the event of lag of the mercury 30, has, even if contaminated, a stabilizing influence on the needle 3 and with the approximately simultaneous closure of the mercury switch, the needle 3, although in extreme instances susceptible to slight floating, at once comes to the accurate circuit disclosing position as the button 5 is maintained depressed.

\Vhat is claimed and it is desired to secure by Letters Patent is:

1. A pair of terminals, means for flexing one to contact the other for circuit closing therebetween, a container mounted on said flexing terminal for movementtherewith and having a pair of terminals, and mercury located during said flexing to close a circuit between said container terminals during the movement of said three terminals.

2. A pair of terminals, means for flexing one to contact the other for circuit closing there'cetween, a container having a pair of terminals, mercury located durin said flexing to close a circuitbetween sai I container terminals, and an electric current supply additional terminal operable for closing in sequence after said mercurycircuit closing.

3. A switch device embodying a. container, a pair of terminals therein, mercury in said container relatively shiftable as to the terminals for closing and opening electric conductor connection therebetween, an additional electric circuit supply switch, and operating means for the latter switch closing after the mercury switch closing and opening before the mercury switch opening.

at. A push button, a mercury containerhaving a pair of terminals, and a mounting for the container shiftable by said button axially of the button for rolling the mercury toward and away from said terminals for switch closing and opening operations.

5. A push button, a mercury container havin g a pair of terminals, said container mounted to be shifted by said button for rolling the mercurytoward and away from said terminals for switch closing and opening opera- P5 tions, and an additional switch to be operated by said buttons further depression after eflecting said mercury switch'operation.

6. A push button, a mercury container having a. pair of terminals, a mounting for the1 container shiftable by said button for rolling the mercury toward and away from said terminals for switch closing and opening operations, and an additional switch to be operated by said mounting further shifting after effecting said mercury switch operation, said additional switch being in series with the mercury switch and effective for precluding circuit making or breaking by said mercury.

7. A switch device embodying a. terminal switch, a mercury switch and an additionai switch, and control means for operating the additional switch after terminal switch closing and before mercury switch opening.

8. A switch device comprising a plurality of switches in parallel, terminals for said switches, and an actuator for shifting a terminal of one switch and directly causing an additional terminal to connect a pair of terminals.

9. A container, a pair of terminals therein, mercury in said container relatively shiftable as to the terminals for closing and opening electric conductor connection therebetween in thereby providing a switch device, an additional switch in parallel with the container terminals, and actuating means for approximating simultaneous operation of the mercury and switch.

10. In combination switches in parallel, one of which is fluid, and actuating means for the switches approximating simultaneous switch operation, the departure from simultaneous opening providing for full current flow through the first closed switch prior to the closing of an additional switch.

11. A mercury switch embodying a tiltahle container, an additional switch in parallel with the mercury switch, and actuating means for approximating simultaneous opening and closing of said switches, the departure from simultaneous opening providing for full current flow through the first closed switch prior to the closing of an additional switch.

12. A mercury switch embodying a tiltable container, a second switch in parallel with the mercury switch, a third switch in series with the mercury and second switch, and actuating means for approximating si- 7 multaneous closing of said mercury and sec- 0nd switches and delayed closing of the third switch, with converse sequence in switch opening.

In witness whereof I aifix my signature. CARL H. KUHLMAN. 

